Gaging device for electrolysis cell



Sept. 28, 1965 J. D. MUELLER ETAL 3,208,152

GAGING DEVICE FOR ELECTROLYSIS CELL Filed Feb. 29. 1960 2 Sheets-Sheet 1 l 28, 1965 J. D. MUELLER ETAL 3,208,152

GAGING DEVICE FOR ELECTROLYSIS CELL Filed Feb. 29, 1960 2 SheetsSheet 2 United States Patent 3,2.il8,152 GAGENG DEVICE FOR ELECTROLYSIS CELL John D. Mueller and .l. D. Russell, Baton Rouge, 1a., assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia Filed Feb. 29, 196i), Ser. No. 11,636 1 Claim. (Q1. 33-180) This invention relates to apparatus for the production of alkali metals, particularly sodium, by electrolysis in cells of the Downs type. In particular, the invention relates to a gaging device for determining the exact orientation of a unitary cathode assembly within its surrounding cell walls.

Alkali metals, especially sodium, are produced by the electrolysis of fused baths of halide compounds or mixtures of halide compounds containing the desired metals. For example, in the production of sodium, a fused bath containing a mixture of the chlorides of sodium and calcium is electrolyzed at a temperature of from about 575 to 700 C. to release elemental sodium. This operation has long been carried out in Downs type sodium cells such as disclosed in U.S. Patent 1,501,756, and variations of this cell are in commercial use today. The anodes and the cathode of these cells are enclosed within a cell wall above which rests a collector for separation of the products. These cells are characterized particularly by a plurality of bottom-mounted vertically aligned cylindrical anodes, each of which is surrounded by a cylindrical opening of a unitary cathode assembly. Each cathode cylindrical opening is of slightly larger diameter than the diameters of the anodes and thus define annular openings between anode and cathode. These annular openings constitute electrolysis zones, and within these zones are usually placed cylindrical shaped foraminous metal diaphragms. Ideally each of the cylindrical members should remain coaxially concentric at any given elevation throughout the entire period of operation of the cell. The cathode assembly and the cell walls in particular however are susceptible to displacement because of thermally induced stresses produced during operation of the cell.

Thus, when producing sodium from such cells it is important that the anode, cathode (more specifically, cathode openings) and diaphragm are maintained in careful predetermined alignment with each other to insure the most efficient production. In large commercial cells coaxial concentric alignment of the anodes, cathode openings, and diaphragms is extremely difiicult to maintain because after startup the cell temperature rises from room temperature to several hundred degrees centigrade. This produces changes in dimensional relationship between the various cell components, particularly the relationship between the cathode and the cell wall. These changes are considerable, and even small changes in the lateral or vertical displacement of the cathode produce major changes in the coaxial concentric relationship between anode, cathode openings and the diaphragms.

In particular, the relationship between anode, cathode and diaphragm is disturbed when it becomes necessary to make a diaphragm change. Thus, even though a cell remains in operation for many months, or even years, before the complete cell must be rebuilt, it is nevertheless necessary to remove the upper portion of the cell (including the collector to which are attached the diaphragms) on the average of once every 20 days in order to replace the diaphragms. The collector-diaphragm subassembly is thus removed and new diaphragms attached to the collector. It is extremely difiicult however to replace the collector-diaphragm sub-assembly so that the anodes, cathode and diaphragms are in their proper precise relationship with respect to each other. The present method of aligning anodes, cathode and diaphragms is to feel within the annular openings with rods or bars while moving the extremely heavy collector-diaphragm sub-assembly on top of the cell wall and thus to guess when the diaphragms are in proper coaxial concentric alignment. This is especially hazardous because the anodes and cathode are submerged beneath molten cell bath which has a temperature of several hundred degrees centigrade. Quite obviously then, this type of gaging is unsatisfactory, and also cells so aligned do not operate at the higher current efiiciencies of which they are capable when properly aligned. The importance of getting the highest current etficiences possible is appreciated when it is realized that an average overall improvement of even a small fraction of 1 percent in a commercial establishment employing a large group of operating cells, is worth many thousands of dollars.

A major and specific need accordingly has existed for a method or device for establishing the precise coaxial concentric relationship between the anodes, cathode cylindrical openings and the diaphragms.

Accordingly it is an object of the present invention to provide a new apparatus for gaging and determining the precise coaxial concentric alignment of anode, cathode and diaphragm of an electrolysis cell, and thus in particular to improve the current efiiciency of an operating cell. More specifically, it is an object of the present invention to provide new and novel apparatus for gaging and Ge tel-mining the precise lateral and vertical orientation of a unitary cathode assembly, having cylindrical openings, with reference to its surrounding cell wall so as to enable proper coaxial concentric alignment of these cylindrical openings with reference to diaphragms which are inserted therein.

These and other objetcs of the invention will be better understood by reference to the drawings wherein:

FIGURE 1 is an isometric view of a standard cell with cell wall broken away showing a gaging device or apparatus fitted therein.

FIGURE 2 is a schematic representation demonstrating the principle applicable to proper alignment or calibration of the device as upon a standard cell.

FIGURE 3 is a sub-assembly of the gaging apparatus providing gaging means for determining and fixing the proper relationship between cathode assembly and surrounding cell wall, as in a standard cell, and

FIGURE 4 shows a suitable leveling means for adjustment of the base of the apparatus as upon a cathode assembly of a standard cell.

Thus, the foregoing and other objects are achieved in accordance with an embodiment of the present invention which comprises apparatus for gaging the precise lateral and vertical orientation of a unitary cathode assembly within its surrounding cell wall. By precise determina tion and location of the unitary cathode assembly with respect to its surrounding cell wall, a collector-diaphragm sub-assembly, i.e., a collector to which is attached cylindrical diaphragms corresponding in number to the cylin drical openings within the unitary cathode assembly, can be placed in proper relationship with the cell wall such that the cylindrical diaphragms will extend downwardly into the cathode cylindrical openings and in such position that the cathode cylindrical openings and the diaphragms will be coaxial concentrically aligned.

The preferred mode of establishing the ideal relationship between a unitary cathode assembly and its surrounding cell wall is to take measurements on these members relative to each other on a non-operating cell built to a prescribed standard and not subject to thermal induced changes. Ideally, of course, it is preferable that the centers of the cylindrical openings within the unitary cathode assembly and the cell wall of the standard cell be plumb with the center of the earth. According to this invention then the base of the gaging apparatus can be aligned with the centers of the cylindrical openings, the relationship fixed, and then the relationship of the cell wall thereto also determined, and fixed. This sets the apparatus whereby it can now be employed to check the degree of similarity between a given operating cell and the standard cell. When the apparatus is inserted in an operating cell, the degree to which the operating cell is oif can then be measured, that is, the extent to which the cathode means is displaced with respect to the cell wall. After transcribing the precise lateral and vertical orientation of the cathode means to the cell wall or superstructure, the collector-diaphragm sub-assembly can then be accurately installed whereby the diaphragm means are coaxial and concentric with respect to the cylindrical openings in the cathode means. This invention will be further understood from the following detailed description thereof as illustrated by reference to the accompanying drawings.

Where identifying numbers in the drawings are the same they refer to corresponding or identical elements.

Referring to FIGURE 1 is shown an isometric view of a standard or dummy cell 20 With cell wall 21 broken away showing an embodiment of the invention fitted therein. The standard cell 20 consists of a cell shell 21 mounted upon a base 70. Within the cell shell 21 is located a cathode assembly 30 having cylindrical openings 31 31 31 and 31 which correspond generally with those cathode openings of an operating cell. The base portion of the apparatus is composed of four elongated members or legs, 11 11 11 11 lying in a plane at right angles to each other and extending outwardly from a shaft 9. Upon the lower sides of the legs 11 are afiixed a pair of knife edges 12 12 and bifurcated members 41, 42 equipped with vertically adjustable screws 13;, 13 The latter adjustable screws 13 constitute means for periodically leveling and adjusting the lower portion of the apparatus 10 in proper parallel relationship with the plane defined by the top of the cylindrical openings 31 31 31 31 or the top of the unitary cathode assembly 30 as the knife edges wear. The bifurcated members 41, 42 also provide a means for grasping the cathode assembly 30 to prevent indiscriminate lateral .movement or shifting of the apparatus 10. Thus, the separate branches of the bifurcated members are of just suflicient distance apart that they straddle the narrow parts or webbed portions between the individual cathode cylindrical openings thereby preventing angular displacement, or major lateral movement, of the apparatus 10. In other words, the distance between the bifurcated members is sufficiently restricted so that the projecting portions of the bifurcated members are free to grasp only upon the narrower portions of the cathode webbing and therefore lateral movement as well as angular movement is restricted. This feature permits easy and convenient alignment of the base portion of the apparatus 10 upon an operating cell, adjustments having been made with the standard cell 20.

Referring to FIGURE 4 is shown the details of one of the bifurcated members 41, the member 42 being similar in all details. The prongs 43 43 are generally afiixed to a solid member 44 which is secured to a leg 11 by means of bolts 45 45 and nuts 46 46 via the L shaped brackets 70 and 70 which are welded to the member 11. The prongs 43 are so spaced as to extend slightly beyond the partitioning walls between a pair of cathode cylindrical openings 31 and each project downwardly so as to extend into a cylindrical opening 31 a slight distance. An adjustable screw 13 extends through the leg 11 and solid member 44, and provides means of leveling the lower portion of the apparatus 10 upon the cathode 30 so that it is parallel therewith. The screw 13 is locked in position by the lock nut 71.

The structure of FIGURE 4, like that of the other figures, represents only one embodiment of this invention. Other embodiments will be visualized in light of the present disclosure, such as dispensing with the L shaped brackets and welding the member 11 directly to the member 44.

After the base portion of the apparatus 10 is adjusted upon the cathode assembly 30 the adjustable devices 33 33 affixed upon the terminal portions of the arms 34 34 can be aligned upon indicia marks 22 22 scribed upon the cell wall 21. The details of one of these adjustable devices 33 is shown in FIGURE 3, both members 33 and 33 being similar in all details. A base portion of the adjustable device 33 is secured to an arm 34. Loosening by turning of the adjustment knob 36 permits free vertical and rotational movement of the member 37. The rod 39 is also vertically movable by turning and loosening of the knob 40. Thus, the member 37 which is clamped within the member 60 is free to turn or rotate within that member and is also free to lateral displacement except as limited by contact of the stop 61 or knuckle joint 62 with the member 60. Loosening of these members in this manner thus permits a wide range of movement of the pedestal or foot 50, since it is movable within the range of freedom permitted by the adjustment described in connection with member 60. In this regard, flexibilty and movement of the pedestal 50 is also permitted by loosening or turning of the ad justment knob which permits limited angular and linear displacement of the rod portion 39 of the pedestal 5t} within the member 63. The vertical displacement of the member 39 within the member 63 is limited Only by physical contact with the stop 64 and the pedestal 50. The member 63, and consequently also the pedestal 50, can also be displaced by moving of the member 63 along the rod 65 except as limited by physical contact with the joint 62. By tightening of the knobs 36, 40 the position of the foot can be aligned and then fixed in any position. Thus, after leveling the device 10 upon the cathode assembly 30 the foot 50 is adjusted or aligned upon the indicia marks 22 22 and then tightly fixed in this position.

The principle of using the apparatus 10 is illustrated by reference to schematic FIGURE 2 which shows the method of aligning the apparatus 10 upon the standard cell so as to establish the precise relationship between the cyldrical openings of the cathode and a location upon the cell wall 21; or, in other words, this figure shows the principle of measuring the relationship between the cathode assembly and the surrounding cell wall so that the precise relationship of the cylindrical openings with the cell wall of the standard cell can be reestablished in an operating cell. The base of the lower portion of the apparatus 10 is first adjusted upon a cathode assembly 30. Thus, the prongs 43 43 43 43 of the bi furcated members 41, 42 are fixed upon a cathode assembly 30. The apparatus 10 is then leveled by adjustment of the adjustable screws 13 which causes some pivoting about the knife edges 12 12 until the lower portion of the apparatus 10 is level or parallel to top of the cathode assembly. On a level above the members constituting the base of the apparatus lie the pedestals 50 50 of the adjustable devices 33. These are aligned upon the indicia marks 22 22 The pedestals 50 50 of the adjustable devices 33 are then locked securely in position. This establishes the proper relationhip between the cathode assembly 30 and the surrounding cell wall 21 within an ideal FOI' standard cell. The next step is then to establish this same precise relationship between the cylindrical openings of the cathode 30 and the cell wall 21 in an operating cell, this relationship being slightly variableover a period of time in an operating cell because of thermal stresses altering this relationship. Thus, the device 10 so aligned can be then transported to an operating cell and the base portion of the device 10 lowered and submerged within the molten bath.- Qf 1.; fi ls T device is quite easily positioned upon the cathode assembly of the operating cell by laterally moving the apparatus 10 until the prongs of the bifurcated members 41, 42 grasp the cathode 30. It will be ob served that the prongs of the bifurcated member 41, 42 need not be centered precisely at any exact point upon the Walls between the pairs of cylindrical openings 31 inasmuch as the bifurcated members 41, 42 and the adjustable gaging devices 33 33 lie generally within the same vertical plane. Having thus fitted the base portion of the apparatus 10 upon the cathode of the operating cell the pedestals 50 50 rest adjacent the upper surfaces of the cell wall of the operating cell at positions whereupon the collector can be aligned to insure proper positioning of the diaphragms. New indicia marks are thus inscribed upon the wall of the operating cell at these positions and the device 10 then removed from the operating cell. In this regard, two possible situations exist: the cathode assembly may be level or horizontally situated with respect to the wall of the operating cell or it may not be level with respect to the cell wall but instead slightly tipped. Where the cathode assembly is level all that is necessary to establish the proper relationship between the cathode and the cell Wall is simply to inscribe new indicia marks upon the wall of the operating cell. This done, the collectordiaphragm assembly can be aligned upon the marks and the diaphragms of the collector-diaphragm assembly will extend downwardly into the cathode openings coaxial concentrically therewith. On the other hand, where the cathode assembly is not quite level with respect to the cell wall, then the wall of the cell can be level at the locations where the collector-diaphragm will be supported. Thus, by physical measurement from any given portion on the adjustable devices, as from the lowermost portion of the member 63 downward to the top of the cell wall, it can be determined whether or not the wall is level with or on the same plane with regard to the cathode. If it is found that the cathode and the wall are not level then the wall can be built up by the use of shims or in some similar manner until the cathode and cell wall are horizontal one With regard to the other. When such horizontal disposition is established, new indicia marks are then inscribed. The collector-diaphragm sub-assembly is then lowered upon the cell and as the diaphragms are submerged into the molten bath the collector is lowered and aligned upon the new indicia marks. In this manner, coaxial concentricity between the cathode openings and the diaphragm is established.

The apparatus was employed in the manner described in the alignment of the collector-diaphragm sub-assemblies 6 of a very large number of cells. It was found that the average overall current efliciency of these cells between diaphragm changes was increased by 2 percent over the average current efiiciency of cells reassembled after diaphragm changes by conventional methods.

The time required before necessary diaphragm changes had to be made were also extended by at least percent.

It is quite apparent that the apparatus of this invention is susceptible to considerable variation without departing from the spirit and scope of the invention.

Having described the invention What is claimed is:

We claim:

Apparatus for gaging, in an operating cell wherein the cathode is submerged in molten cell bath, the precise lateral and vertical orientation of a cylindrical opening Within a unitary cathode assembly enclosed by its surrounding cell wall in relationship with a cylindrical opening within a unitary cathode assembly in a standard cell relative to its surrounding ceil wall, said opening within the cathode assembly of the standard cell being fixed in a predetermined relationship with indicia located upon the surrounding cell wall of the standard cell comprising a structure composed of a base portion and an upper alignment portion, each portion including a plurality of elongated members projecting perpendicularly from a shaft and so distributed as to lie within two parallel planes, the elongated members defining the base portion being provided with a pair of knife edges afiixed thereto on opposite sides of the shaft, and a pair of vertically adjustable screws each located on opposite sides of the shaft on a line substantially perpendicular to a line through the knife edges to define a plane perpendicular to said shaft, said screws and knife blades being used for leveling and holding the structure in proper parallel relationship with the cylindrical opening within the cathode assembly of the standard cell, and elongated members of the upper alignment portion being provided with adjustable means for fixing said structure in definite relationship with the surrounding cell wall so as to preserve the precise relationship between the cylindrical opening and the cell wall of the standard cell whereby the apparatus is then ready for transport and gaging of an operating cell.

References Cited by the Examiner UNITED STATES PATENTS 444,865 1/91 Welles 3317l 2,912,750 11/59 Carlisle et al.

ISAAC LISANN, Primary Examiner. 

